The present invention relates to mountings for flexure units that are used as hinges, specifically on orthosis to provide adjustability of the angular position of the ends of the flexure units about mounting pins used for the ends. This adjustment provides a variable assist for toe lift on an ankle joint orthosis or for the motions of other joints if so used.
Flexure units are used to provide joint motion, such as at an ankle joint, between a leg supported shell and a foot shell or stirrup. Flexure units or flexures are short columns or straps of polyurethane or other suitable thermoplastic materials. The column or strap lengths have sufficient thickness to provide a resilient bendable coupling connected between two components, for example, two parts of an orthosis shell. The flexure units function like a spring loaded hinge, and can be mounted in pairs on opposite sides of the ankle joint, for example. When used in pairs the flexure units form a joint system with a single axis of rotation passing through the flexure column midsections, that is, the elastomeric or polyurethane center portions of the flexure length. Flexures are secured, generally on pins, into shaped end cavities within the two hinged parts, such as components of a typical orthosis, including a lower leg shell and the foot support component which is called a foot shell. The elastomeric column will provide a biasing force to urge the toe of the person wearing the orthosis upwardly. The amount of toe lift force needed may be different for wearers, and can change over time for a variety of reasons.
It has been found in the prior art that flexure units can be provided with a preset angular configuration that when secured to the mounting components on the orthosis shell, the parts that are hinged together will be at an angle and when worn will provide a bias force. In the case of an ankle joint the toe lift force can be increased by angling the central longitudinal axis of the flexure unit.
In many cases it is desirable to have an adjustable amount of resilient force tending to lift the toe of a foot supported in a foot shell for meeting individual patient""s needs.
The present invention relates to end supports for flexure hinge units, which are generally mounted in pairs to form a resilient pivoting joint. Flexure units that are secured between two parts of an orthosis shell including a leg shell and a foot shell, form an ankle joint hinge. At least one end of each flexure unit is mounted on the two parts, respectively, through adjustable housings that permit a change in the xe2x80x9cat restxe2x80x9d angular position of the flexure unit mounted end relative to a support on the shell. The adjustment of the angular position of the one flexure end results in the ability to adjust assisting or lifting force on a foot shell, when the orthosis is worn. For example, in an orthosis shell for a foot, the amount the outer end of the foot shell portion is angled upwardly relative to the lower leg shell can be adjusted. When the orthosis is installed, and the foot shell is moved to conform to the ankle position of the wearer, the flexure units will yield to permit conforming, but a biasing force tending to return the foot shell to its at rest position will be provided. The person wearing the shell will have a force providing toe lift. Such lift force can be adjusted with the present invention.
The present invention mounting housings for the flexures include, as shown, a base that mounts onto one orthosis shell part. The base is held from rotating so it stays in position. The base has a support post that receives the end of the flexure unit or column, and a housing fits over the end of the flexure unit. The housing has an opening that fits over and pivots on the post and thus pivots relative to the base and the pivotal position is adjustable. As shown, a pinion and pinion gear drive is provided between the base and the housing at one end of the flexure. The other end of the flexure can be mounted in a conventional rivet or pin support on the other shell part, or if desired it also can be mounted with an angle adjustment housing.
The flexure unit or column used is unrestrained in its center portions between the orthosis shell parts.
The flexure end mounting housing of the present invention thus provides an adjustable angular position of the mounting housing and the end of the flexure unit held therein, about the central axis of the post that mounts the flexure unit.
In the specific form shown, the base mounts a pinion or screw, which engages rack or pinion teeth on the outer end surface of the mounting housing. By turning the pinion, a rack and pinion drive is provided to pivot the mounting housing relative to the base to its desired angular position. The change in angle varies or changes the assisting force for toe lift. The pinion and gear effect can be calibrated so the change in assisting force for each turn of the pinion may be determined.
If desired, both of the mountings for the flexure unit may have this adjustable end supports that can be changed in angular orientation about the mounting axis of the flexure unit relative to its support.
The unrestrained central portion of the flexure forms a hinge, and resiliently conforms to pivoting action to provide an ankle joint or other suitable joint where a controlled pivotal mounting is desired.
In the case of an ankle-foot orthosis, the dorsiflexion/planterflexion of the patient""s ankle can be differently loaded by adjusting the angular position of the mounting housings for the flexure ends relative to their base supports.
Other types of angular adjustment drives between the mounting housings and the base or mounting components can be used. For example various threaded components that would act against portions of the flexure mounting housing to provide a positive change in angular position and hold the mounting housing in such changed angular position can be used.